Make referenced objects unique?

I’m having trouble with something I figured would be trivial to achieve with the built-in functions.

I have a bunch of reference objects, which I would like to turn unique, without affecting the modifiers on top.

But for some reason I can’t get

InstanceMgr.MakeObjectsUnique

function to work. It works fine on instances, but not on references.
The

InstanceMgr.CanMakeObjectsUnique

also returns false, whenever I try it on a reference.

I’ve also tried to use the

InstanceMgr.MakeControllersUnique

and the

InstanceMgr.MakeModifiersUnique

just to see if that made a difference. The modifiers can be turned unique just fine.

How would I go about turning all my reference unique?